JP2008095000A - Easily adherable highly elastic polyimide film and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyimide film having, in combination, high tensile break strength, high tensile modulus and rather low linear expansion coefficient and excellent in surface adhesion. <P>SOLUTION: A polyimide comprising 1-30 mol% polyimide (a) from oxydiphthalic acid and bis(4-aminophenoxy)benzene and 70-99 mol% polyimide (b) from pyromellitic acid and/or biphenyl tetracarboxylic acid and a diamine having benzoxazole skelton and/or phenylene diamine is provided, the polyimide film obtained from the polyimide and having ≥300 MPa tensile break strength and ≥5 GPa tensile modulus is provided, a copper-clad laminate, a printed circuit board and a multilayer circuit board using the polyimide film are also provided. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  In the present invention, a specific polyimide and a specific polyimide are mixed and / or co-contracted at a specific ratio, both of which have a high tensile breaking strength and a high tensile elastic modulus, have a low linear expansion coefficient, and excellent adhesion. Regarding polymerized polyimide, polyimide film with high tensile fracture strength and tensile modulus, both in a specific range with low linear expansion coefficient and excellent adhesion and heat resistance, and copper-clad laminate using this film The present invention relates to a board and a multilayer circuit board.

  Polyimide films have very little change in physical properties in a wide temperature range from −269 ° C. to 300 ° C., and therefore, applications and uses in the electric and electronic fields are expanding. In the electric field, for example, it is used for coil insulation of vehicle motors, industrial motors, etc., and insulation of aircraft electric wires and superconducting wires. On the other hand, in the electronic field, for example, it is used for a flexible printed circuit board, a base film of a film carrier for semiconductor mounting, and the like. Thus, the polyimide film is widely used in the electric and electronic fields as a highly reliable film among various functional polymer films. Recently, however, major problems have become apparent with the refinement of the electric and electronic fields. For example, a printed circuit board made of a polyimide film base material in which copper is copper-clad by vapor deposition or plating has a tendency that the adhesive strength of the copper layer is lowered due to a change with time and an environmental change, and further peeling occurs.

In addition, ceramic has been conventionally used as a material for base materials of electronic components such as information communication equipment (broadcast equipment, mobile radio equipment, portable communication equipment, etc.), radar, high-speed information processing devices, and the like. A base material made of ceramic has heat resistance, and can cope with an increase in the frequency band (reaching the GHz band) of information communication equipment in recent years. However, ceramics are not flexible and cannot be thinned, so the fields that can be used are limited.
For this reason, studies have been made to use a film made of an organic material as a base material for an electronic component, and a film made of polyimide and a film made of polytetrafluoroethylene have been proposed. A film made of polyimide has excellent heat resistance and has the advantage that the film can be thin because it is tough. However, there are concerns about problems such as low signal strength and signal transmission delay when applied to high-frequency signals. However, the tensile strength at break and the tensile modulus are still insufficient, and the linear expansion coefficient is too large. A film made of polytetrafluoroethylene can handle high frequencies, but the tensile modulus is low, so the film cannot be made thin, the adhesion to metal conductors and resistors on the surface is poor, and the coefficient of linear expansion However, it is problematic in that it is not suitable for the production of a circuit having fine wiring due to a large dimensional change due to temperature change. Thus, a film having sufficient physical properties for a substrate having heat resistance, high mechanical properties, and flexibility has not been obtained yet.
As a polyimide film having a high tensile modulus, a polyimide benzoxazole film made of polyimide having a benzoxazole ring in the main chain has been proposed (see Patent Document 1). A printed wiring board using the polyimide benzoxazole film as a dielectric layer has also been proposed (see Patent Document 2 and Patent Document 3).
Polyimide benzoxazole films consisting of polyimides with these benzoxazole rings in the main chain have improved tensile tensile strength and tensile elastic modulus and are within the range of satisfactory linear expansion coefficients. In spite of its physical properties, it has problems such as insufficient surface properties in terms of adhesion.

Various proposals have been made to improve the adhesion of polyimide with excellent physical properties. For example, a polyimide film that has a thermoplastic resin layer on at least one surface of a polyimide film that does not have adhesion (see Patent Document 4), a polyimide film And at least a two-layer film in which a film made of polyamide resin is laminated (see Patent Document 5).
Even though those with a thermoplastic resin layer on these polyimide films can be satisfied in improving the adhesiveness, the low heat resistance of these thermoplastic resins will ruin the heat resistance of the folded polyimide film. Had a trend.
Japanese Patent Laid-Open No. 06-056792 Japanese National Patent Publication No. 11-504369 Japanese National Patent Publication No. 11-505184 Japanese Patent Laid-Open No. 09-169088 JP 07-186350 A

    It is an object of the present invention to provide a polyimide and a polyimide film which have both a high tensile breaking strength and a high tensile elastic modulus, a specific range having a low linear expansion coefficient, and excellent adhesion.

As a result of intensive studies, the present inventors have found that a polyimide in which a specific polyimide and a specific polyimide are mixed and / or cocondensation-polymerized at a specific ratio has both high tensile rupture strength and tensile elastic modulus and a low linear expansion coefficient. It is in a specific range, and has a higher level of adhesion, heat resistance, and flexibility. Polyimide film from this polyimide and insulation reliability and lightness (light thinness) using this film as an insulating layer It is intended to provide a circuit board and a multilayer circuit board that can also achieve the above.
That is, the present invention has the following configuration.
1. A polyimide having a structural unit of the following [Chemical Formula 1], wherein at least R1 is a residue of an aromatic tetracarboxylic acid selected from [Chemical Formula 2], and R2 is an aromatic diamine selected from [Chemical Formula 3] 1-30 mol% of polyimide (a) having a residue,

少なくとも芳香族テトラカルボン酸類の残基としてピロメリット酸残基及び／又はビフェニルテトラカルボン酸残基、芳香族ジアミン類の残基としてベンゾオキサゾール骨格を有するジアミンの残基及び／又はフェニレンジアミンの残基を有するポリイミド（ｂ）を７０〜９９モル％とを含むことを特徴とするポリイミド。
２． 前記１のポリイミドから得られる引張破断強度が３００ＭＰａ以上、引張弾性率が５ＧＰａ以上であるポリイミドフィルム。
３． 面方向での線膨張係数が０〜３０ｐｐｍ／℃である前記２のポリイミドフィルム。
４． 前記２又は３いずれかのポリイミドフィルムを基板として用いた銅張積層板。
５． 前記４の銅張積層板の銅層を一部除去して回路パターンを形成してなるプリント配線板。
６． 前記２〜５いずれかのポリイミドフィルム及び／又はプリント配線板を用いた多層回路基板。

At least pyromellitic acid residue and / or biphenyltetracarboxylic acid residue as aromatic tetracarboxylic acid residue, diamine residue having benzoxazole skeleton and / or phenylenediamine residue as aromatic diamine residue A polyimide comprising 70 to 99 mol% of a polyimide (b) containing
2. A polyimide film having a tensile strength at break of 300 MPa or more and a tensile modulus of elasticity of 5 GPa or more obtained from the polyimide of 1 above.
3. Said 2 polyimide film whose linear expansion coefficient in a surface direction is 0-30 ppm / degrees C.
4). A copper-clad laminate using the polyimide film of either 2 or 3 as a substrate.
5. A printed wiring board formed by removing a part of the copper layer of the copper-clad laminate of 4 to form a circuit pattern.
6). A multilayer circuit board using the polyimide film and / or printed wiring board according to any one of 2 to 5 above.

  A polyimide obtained by mixing and / or co-condensation-polymerizing a specific polyimide and a specific polyimide of the present invention at a specific ratio has both a high tensile breaking strength and a high tensile elastic modulus, and has a specific range with a low linear expansion coefficient. Circuit board that has higher levels of heat resistance, heat resistance, and flexibility, and that can achieve insulation reliability and lightness (light thinness) by using the polyimide film from this polyimide and this film as an insulating layer As a multilayer circuit board, it has high tensile elastic modulus, tensile rupture strength, and low coefficient of linear expansion in a specific range, and its surface in contact with the metal has excellent adhesiveness. It is extremely useful for circuit boards, multilayer circuit boards, bonding films with metal foils (layers), and the like.

  The polyimide and film of the present invention are polyimides having a structural unit of [Chemical Formula 1], wherein at least R1 is a residue of an aromatic tetracarboxylic acid selected from [Chemical Formula 2], and R2 is selected from [Chemical Formula 3] 1 to 30 mol% of the polyimide (a) having a residue of aromatic diamine, and at least as a residue of aromatic tetracarboxylic acid, a pyromellitic acid residue and / or a biphenyltetracarboxylic acid residue, aromatic A polyimide containing 70 to 99 mol% of a polyimide (b) having a diamine residue having a benzoxazole skeleton and / or a phenylenediamine residue as a diamine residue, and a polyimide film therefrom.

The polyimide in the present invention is a polyimide having a structural unit of [Chemical Formula 1], wherein at least R1 is a residue of an aromatic tetracarboxylic acid selected from [Chemical Formula 2], and R2 is selected from [Chemical Formula 3]. 1-30 mol% of the polyimide (a) having an aromatic diamine residue, and at least a pyromellitic acid residue and / or a biphenyltetracarboxylic acid residue as an aromatic tetracarboxylic acid residue, an aromatic diamine Is a polyimide containing 70 to 99 mol% of a polyimide (b) having a diamine residue having a benzoxazole skeleton and / or a phenylenediamine residue as the residue, and the film is, for example, an aromatic tetracarboxylic acid ( Pyromellitic acid and / or biphenyltetracarboxylic acid residues (including anhydrides and derivatives) with aromatic diamines A diamine having a benzoxazole skeleton and / or phenylenediamine is reacted in a solvent to obtain a polyamic acid which is a precursor of (b), while aromatic tetracarboxylic acids such as 4,4′-oxydiphthalic acid residue, Reaction with 1,3-bis (4-aminophenoxy) benzene as an aromatic diamine in a solvent to obtain a polyamic acid which is a precursor of (a) and mixing them, or both of these aromatic tetra A polyamic acid solution, which is a polyimide precursor obtained by reacting a carboxylic acid and an aromatic diamine simultaneously in a solvent, is obtained, and these solutions are cast on a support and dried to obtain a polyimide precursor film (green Can also be manufactured by a method in which the precursor film is further heat-treated and imidized to obtain a polyimide film. Kill.
As aromatic diamines having a benzoxazole skeleton (structure) used in (b) in the present invention (aromatic diamines, amide-bonded derivatives of aromatic diamines and the like are collectively referred to as aromatic diamines hereinafter), The following compounds can be exemplified.

Among these, amino (aminophenyl) benzoxazole isomers are preferable from the viewpoint of ease of synthesis. Here, “each isomer” refers to each isomer in which two amino groups of amino (aminophenyl) benzoxazole are determined according to the coordination position (eg, [Chemical Formula 4] to [Chemical Formula 7] above). Each compound described in the above). These diamines may be used alone or in combination of two or more.
Examples of the phenylene diamine in the present invention include p-phenylene diamine, o-phenylene diamine, m-phenylene diamine, and the like, preferably p-phenylene diamine.
In the present invention, pyromellitic acid, biphenyltetracarboxylic acid (biphenyltetracarboxylic acid and its) are used as aromatic tetracarboxylic acids (collectively referred to as acids, anhydrides, amide bond derivatives, hereinafter also referred to as aromatic tetracarboxylic acids). Dianhydrides (PMDA) as well as their lower alcohol esters) are used. Of the biphenyltetracarboxylic acids, 3,3 ′, 4,4′-biphenyltetracarboxylic acid or its dianhydride is preferred.
In the present invention, the aromatic diamine having the benzoxazole structure, the phenylene diamine, and the diamine having the skeleton of [Chemical Formula 3] are used in an amount of 70 mol% or more, preferably 85 mol% or more of the total diamine having an imide structure. .
In the present invention, as the aromatic tetracarboxylic acids, pyromellitic acid, biphenyltetracarboxylic acid, and tetracarboxylic acid having a skeleton of [Chemical Formula 2] are 70 mol% or more, preferably 85 mol% or more of the total carboxylic acid. It is preferable to use it.

  Without being limited to the diamine, the following diamines can be used as long as they are less than 30 mol% of the total diamines. Examples of these diamines include 4,4′-bis (3-aminophenoxy) biphenyl, bis [4- (3-aminophenoxy) phenyl] ketone, bis [4- (3-aminophenoxy) phenyl] sulfide. Bis [4- (3-aminophenoxy) phenyl] sulfone, 2,2-bis [4- (3-aminophenoxy) phenyl] propane, 2,2-bis [4- (3-aminophenoxy) phenyl]- 1,1,1,3,3,3-hexafluoropropane, m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, m-aminobenzylamine, p-aminobenzylamine,

3,3′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, 4,4′-diaminodiphenyl ether, 3,3′-diaminodiphenyl sulfide, 3,3′-diaminodiphenyl sulfoxide, 3,4′-diaminodiphenyl sulfoxide 4,4′-diaminodiphenyl sulfoxide, 3,3′-diaminodiphenyl sulfone, 3,4′-diaminodiphenyl sulfone, 4,4′-diaminodiphenyl sulfone, 3,3′-diaminobenzophenone, 3,4′- Diaminobenzophenone, 4,4′-diaminobenzophenone, 3,3′-diaminodiphenylmethane, 3,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylmethane, bis [4- (4-aminophenoxy) phenyl] methane, 1 , 1-Bi [4- (4-aminophenoxy) phenyl] ethane, 1,2-bis [4- (4-aminophenoxy) phenyl] ethane, 1,1-bis [4- (4-aminophenoxy) phenyl] propane, 1 , 2-bis [4- (4-aminophenoxy) phenyl] propane, 1,3-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl ]propane,

1,1-bis [4- (4-aminophenoxy) phenyl] butane, 1,3-bis [4- (4-aminophenoxy) phenyl] butane, 1,4-bis [4- (4-aminophenoxy) Phenyl] butane, 2,2-bis [4- (4-aminophenoxy) phenyl] butane, 2,3-bis [4- (4-aminophenoxy) phenyl] butane, 2- [4- (4-aminophenoxy) Phenyl] -2- [4- (4-aminophenoxy) -3-methylphenyl] propane, 2,2-bis [4- (4-aminophenoxy) -3-methylphenyl] propane, 2- [4- ( 4-aminophenoxy) phenyl] -2- [4- (4-aminophenoxy) -3,5-dimethylphenyl] propane, 2,2-bis [4- (4-aminophenoxy) -3,5-dimethylphen Le] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane,

1,4-bis (3-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, 4,4′-bis (4-aminophenoxy) ) Biphenyl, bis [4- (4-aminophenoxy) phenyl] ketone, bis [4- (4-aminophenoxy) phenyl] sulfide, bis [4- (4-aminophenoxy) phenyl] sulfoxide, bis [4- ( 4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] ether, bis [4- (4-aminophenoxy) phenyl] ether, 1,3-bis [4- (4-aminophenoxy) ) Benzoyl] benzene, 1,3-bis [4- (3-aminophenoxy) benzoyl] benzene, 1,4-bis [4- (3 Aminophenoxy) benzoyl] benzene, 4,4′-bis [(3-aminophenoxy) benzoyl] benzene, 1,1-bis [4- (3-aminophenoxy) phenyl] propane, 1,3-bis [4- (3-aminophenoxy) phenyl] propane, 3,4'-diaminodiphenyl sulfide,

2,2-bis [3- (3-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, bis [4- (3-aminophenoxy) phenyl] methane, 1,1 -Bis [4- (3-aminophenoxy) phenyl] ethane, 1,2-bis [4- (3-aminophenoxy) phenyl] ethane, bis [4- (3-aminophenoxy) phenyl] sulfoxide, 4,4 '-Bis [3- (4-aminophenoxy) benzoyl] diphenyl ether, 4,4'-bis [3- (3-aminophenoxy) benzoyl] diphenyl ether, 4,4'-bis [4- (4-amino-α) , Α-dimethylbenzyl) phenoxy] benzophenone, 4,4′-bis [4- (4-amino-α, α-dimethylbenzyl) phenoxy] diphenylsulfone, bis 4- {4- (4-aminophenoxy) phenoxy} phenyl] sulfone, 1,4-bis [4- (4-aminophenoxy) phenoxy-α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4-aminophenoxy) phenoxy-α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4-amino-6-trifluoromethylphenoxy) -α, α-dimethylbenzyl] benzene, 1,3 -Bis [4- (4-amino-6-fluorophenoxy) -α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4-amino-6-methylphenoxy) -α, α-dimethylbenzyl Benzene, 1,3-bis [4- (4-amino-6-cyanophenoxy) -α, α-dimethylbenzyl] benzene,

3,3′-diamino-4,4′-diphenoxybenzophenone, 4,4′-diamino-5,5′-diphenoxybenzophenone, 3,4′-diamino-4,5′-diphenoxybenzophenone, 3, 3'-diamino-4-phenoxybenzophenone, 4,4'-diamino-5-phenoxybenzophenone, 3,4'-diamino-4-phenoxybenzophenone, 3,4'-diamino-5'-phenoxybenzophenone, 3,3 '-Diamino-4,4'-dibiphenoxybenzophenone, 4,4'-diamino-5,5'-dibiphenoxybenzophenone, 3,4'-diamino-4,5'-dibiphenoxybenzophenone, 3,3'- Diamino-4-biphenoxybenzophenone, 4,4′-diamino-5-biphenoxybenzophenone, 3,4 -Diamino-4-biphenoxybenzophenone, 3,4'-diamino-5'-biphenoxybenzophenone, 1,3-bis (3-amino-4-phenoxybenzoyl) benzene, 1,4-bis (3-amino- 4-phenoxybenzoyl) benzene, 1,3-bis (4-amino-5-phenoxybenzoyl) benzene, 1,4-bis (4-amino-5-phenoxybenzoyl) benzene, 1,3-bis (3-amino) -4-biphenoxybenzoyl) benzene, 1,4-bis (3-amino-4-biphenoxybenzoyl) benzene, 1,3-bis (4-amino-5-biphenoxybenzoyl) benzene, 1,4-bis (4-Amino-5-biphenoxybenzoyl) benzene, 2,6-bis [4- (4-amino-α, α-dimethylbenzyl) pheno Si] A part or all of the hydrogen atoms on the aromatic ring in the benzonitrile and the aromatic diamine are halogen atoms, alkyl groups having 1 to 3 carbon atoms or alkoxyl groups, cyano groups, or alkyl groups or alkoxyl group hydrogen atoms. Examples thereof include aromatic diamines substituted with a halogenated alkyl group having 1 to 3 carbon atoms, partially or entirely substituted with halogen atoms, or alkoxyl groups.

  In the present invention, pyromellitic acid and biphenyltetracarboxylic acid as aromatic tetracarboxylic acids are represented by the following [Chemical Formula 17] and [Chemical Formula 18], and tetracarboxylic acids having a skeleton of [Chemical Formula 2] are represented by the following [Chemical Formulas]. 19] and [Chemical 20].

  In the present invention, aromatic tetracarboxylic acids exemplified below other than the above may be used as long as they are less than 30 mol%, preferably less than 15 mol% of the total carboxylic acids.

In the present invention, one or two or more non-aromatic tetracarboxylic dianhydrides exemplified below may be used in combination as appropriate as long as they are less than 30 mol% of the total carboxylic acids.
Non-aromatic tetracarboxylic dianhydrides include, for example, butane-1,2,3,4-tetracarboxylic dianhydride, pentane-1,2,4,5-tetracarboxylic dianhydride, Cyclobutanetetracarboxylic dianhydride, cyclopentane-1,2,3,4-tetracarboxylic dianhydride, cyclohexane-1,2,4,5-tetracarboxylic dianhydride, cyclohex-1-ene-2 , 3,5,6-tetracarboxylic dianhydride, 3-ethylcyclohex-1-ene-3- (1,2), 5,6-tetracarboxylic dianhydride, 1-methyl-3-ethyl Cyclohexane-3- (1,2), 5,6-tetracarboxylic dianhydride, 1-methyl-3-ethylcyclohex-1-ene-3- (1,2), 5,6-tetracarboxylic acid Dianhydride, 1-ethylcyclohexa -1- (1,2), 3,4-tetracarboxylic dianhydride, 1-propylcyclohexane-1- (2,3), 3,4-tetracarboxylic dianhydride, 1,3-dipropyl Cyclohexane-1- (2,3), 3- (2,3) -tetracarboxylic dianhydride, dicyclohexyl-3,4,3 ′, 4′-tetracarboxylic dianhydride,

Bicyclo [2.2.1] heptane-2,3,5,6-tetracarboxylic dianhydride, 1-propylcyclohexane-1- (2,3), 3,4-tetracarboxylic dianhydride, 1 , 3-Dipropylcyclohexane-1- (2,3), 3- (2,3) -tetracarboxylic dianhydride, dicyclohexyl-3,4,3 ′, 4′-tetracarboxylic dianhydride, bicyclo [2.2.1] Heptane-2,3,5,6-tetracarboxylic dianhydride, bicyclo [2.2.2] octane-2,3,5,6-tetracarboxylic dianhydride, bicyclo [2.2.2] Oct-7-ene-2,3,5,6-tetracarboxylic dianhydride and the like. These tetracarboxylic dianhydrides may be used alone or in combination of two or more.

The solvent used when polymerizing aromatic diamines and aromatic tetracarboxylic acid anhydrides to obtain polyamic acid is particularly limited as long as it dissolves both the raw material monomer and the polyamic acid to be produced. Although not preferred, polar organic solvents are preferred, such as N-methyl-2-pyrrolidone, N-acetyl-2-pyrrolidone, N, N-dimethylformamide, N, N-diethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide Hexamethylphosphoric amide, ethyl cellosolve acetate, diethylene glycol dimethyl ether, sulfolane, halogenated phenols and the like.
The concentration of the polyamic acid in the polyamic acid solution obtained by the polymerization reaction is preferably 5 to 40% by mass, more preferably 10 to 30% by mass, and the viscosity of the solution is measured with a Brookfield viscometer (25 ° C.). And from the stability point of liquid feeding, Preferably it is 10-2000 Pa.s, More preferably, it is 100-1000 Pa.s.
The reduced viscosity (ηsp / C) of the polyamic acid in the present invention is not particularly limited, but is preferably 3.0 dl / g or more in order to improve the tensile elastic modulus, tensile breaking strength, and tensile breaking elongation. More preferably, 0.0 dl / g or more.

In the polyimide or polyimide film of the present invention, it is preferable to add and contain a lubricant therein to give fine irregularities on the surface of the layer (film) to improve the adhesion of the layer (film). As the lubricant, inorganic or organic fine particles having an average particle diameter of about 0.03 μm to 3 μm can be used. Specific examples include titanium oxide, alumina, silica, calcium carbonate, calcium phosphate, calcium hydrogen phosphate, calcium pyrophosphate, Examples include magnesium oxide, calcium oxide, and clay minerals.
These fine particles are preferably contained in the range of 0.20 to 2.0 mass% with respect to the polyimide or film. When the content of the fine particles is less than 0.20% by mass, there is not so much improvement in adhesion, which is not preferable. On the other hand, if it exceeds 2.0% by mass, the surface unevenness becomes too large, and even if the adhesiveness is improved, problems such as a decrease in smoothness remain, which is not preferable. These lubricants may be added and contained in the layer (a) as well.

As a method of forming a polyimide film from the polyamic acid solution obtained by the polymerization reaction, a green film is obtained by applying the polyamic acid solution on a support and drying, and then subjecting the green film to a heat treatment. A method of imidization reaction may be mentioned.
The support on which the polyamic acid solution is applied is only required to have smoothness and rigidity sufficient to form the polyamic acid solution into a film, and a drum or belt whose surface is made of metal, plastic, glass, porcelain, etc. And the like. Among them, the surface of the support is preferably a metal, more preferably stainless steel that does not rust and has excellent corrosion resistance. The surface of the support may be plated with metal such as Cr, Ni, or Sn. The surface of the support can be mirror-finished or processed into a satin finish as necessary. In addition, a polymer film such as a polyethylene terephthalate film or a polyethylene naphthalate film can be used as the support.

Application of the polyamic acid solution to the support includes, but is not limited to, casting from a slit base, extrusion through an extruder, squeegee coating, reverse coating, die coating, applicator coating, wire bar coating, etc. Conventionally known solution coating means can be appropriately used.
A polyamic acid solution is formed into a film to obtain a precursor film (green film), which is imidized to obtain a polyimide film. As a specific imidization method, a conventionally known imidation reaction can be appropriately used. For example, using a polyamic acid solution that does not contain a ring-closing catalyst or a dehydrating agent, the imidization reaction proceeds by subjecting it to a heat treatment (so-called thermal ring-closing method), or a polycyclic acid solution containing a ring-closing catalyst and a dehydrating agent. In order to obtain a polyimide film in which the difference in surface orientation between the front and back surfaces of the polyimide film is small, a chemical ring closing method can be mentioned in which an imidization reaction is performed by the action of the above ring closing catalyst and dehydrating agent. The thermal ring closure method is preferred.

100-500 degreeC is illustrated as a heating maximum temperature of a thermal ring closure method, Preferably it is 200-480 degreeC. When the maximum heating temperature is lower than this range, it is difficult to close the ring sufficiently, and when it is higher than this range, deterioration proceeds and the film tends to become brittle. A more preferable embodiment includes a two-stage heat treatment in which treatment is performed at 150 to 250 ° C. for 3 to 20 minutes and then treatment is performed at 350 to 500 ° C. for 3 to 20 minutes.
In the chemical ring closure method, after the polyamic acid solution is applied to a support, the imidization reaction is partially advanced to form a self-supporting film, and then imidization can be performed completely by heating. In this case, the condition for partially proceeding with the imidization reaction is preferably a heat treatment for 3 to 20 minutes at 100 to 200 ° C., and the condition for allowing the imidization reaction to be completely performed is preferably 200 to 400 ° C. For 3 to 20 minutes.

  The polyimide film in the present invention has high tensile strength at break, high tensile modulus, low linear expansion coefficient, and excellent surface adhesion, and the obtained polyimide film has a tensile strength at break as a preferred embodiment. Is a polyimide film having excellent performance with a tensile modulus of 6 GPa or more and a linear expansion coefficient in the plane direction of 0 to 30 ppm / ° C.

The measurement of the coefficient of linear expansion (CTE) in the plane direction in the present invention is as follows.
<Linear expansion coefficient in the surface direction of (b) layer film and multilayer polyimide film>
For the film to be measured, the stretch rate in the MD direction and the TD direction is measured under the following conditions, and the stretch rate / temperature at intervals of 90 ° C. to 100 ° C., 100 ° C. to 110 ° C.,. This measurement was performed up to 400 ° C., and the average value of all measured values from 100 ° C. to 350 ° C. was calculated as CTE (average value). The meanings of the MD direction and the TD direction indicate the flow direction (MD direction; the length direction of the long film) and the width direction (TD direction; the width direction of the long film).
The linear expansion coefficient in the plane direction is an average value of values in the MD direction and the TD direction.
Device name: TMA4000S manufactured by MAC Science
Sample length; 10mm
Sample width: 2 mm
Temperature rise start temperature: 25 ° C
Temperature rising end temperature: 400 ° C
Temperature increase rate: 5 ° C / min
Atmosphere: Argon

Measurements of tensile strength at break and tensile modulus are as follows.
<Measurement of tensile strength and tensile modulus of polyimide film and multilayer polyimide film>
A test piece was prepared by cutting a film to be measured into strips of 100 mm × 10 mm in the MD direction and the TD direction, respectively. Using a tensile tester (manufactured by Shimadzu Corp., Autograph (trade name) model name AG-5000A) under the conditions of a tensile speed of 50 mm / min and a distance between chucks of 40 mm, the tensile modulus and tension in each of the MD and TD directions. The breaking strength and tensile breaking elongation were measured.

EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated more concretely, this invention is not limited by a following example. The physical property evaluation methods in the following examples are as follows except for the above.
1. Reduced viscosity of polyamic acid (ηsp / C)
A solution dissolved in N-methyl-2-pyrrolidone so that the polymer concentration was 0.2 g / dl was measured at 30 ° C. using an Ubbelohde type viscosity tube.

2. Film thickness The film thickness was measured using a micrometer (Millitron 1254D manufactured by Fine Reef Co., Ltd.).

3. Peel strength A masking tape is attached to the metal laminated polyimide film to be measured, and after processing into a pattern with a line width of 1 mm by etching away the copper layer that is not masked with ferric chloride aqueous solution, the direction of 90 degrees The peel strength was defined as the strength required when peeled off. The measurement at room temperature was taken as the initial peel strength, and the peel strength measured after standing in a PCT environment (121 ° C., 100% RH, 2 atoms, 168 hours) was taken as the post-PCT peel strength. According to JIS C6418, a tensile tester (manufactured by Shimadzu Corporation, Autograph (trade name) model name AG-5000A) was used.

[Preparation of polyamic acid solution (1)]
(PMDA / p-DAMBO)
After the inside of a reaction vessel equipped with a nitrogen introduction tube, a thermometer, and a stirring rod was purged with nitrogen, 500 parts by mass of 5-amino-2- (p-aminophenyl) benzoxazole (p-DAMBO) was charged. Next, after adding 5000 parts by mass of N, N-dimethylacetamide and completely dissolving it, Snowtex (trade name) DMAC-ZL (Nissan Chemical Industry Co., Ltd.) in which colloidal silica is dispersed in N, N-dimethylacetamide 40.5 parts by mass (containing 8.1 parts by mass of silica), 485 parts by mass of pyromellitic dianhydride (PMDA), and stirring for 48 hours at a reaction temperature of 25 ° C. A tonic polyamic acid solution (1) was obtained. Ηsp / C of the obtained solution was 4.2 dl / g.

[Preparation of polyamic acid solution (2)]
(ODPA / TPER)
The inside of the reaction vessel equipped with a nitrogen introduction tube, a thermometer, and a stirring rod was purged with nitrogen, and then charged with 930 parts by mass of 1,3-bis (4-aminophenoxy) benzene. Next, 15000 parts by mass of N, N-dimethylacetamide was introduced, and after stirring well so as to be uniform, Snowtex (trade name) DMAC-ZL (Nissan Chemical Co., Ltd.) formed by dispersing colloidal silica in dimethylacetamide 40.5 parts by mass (manufactured by Kogyo Co., Ltd.) (containing 8.1 parts by mass of silica) was added, the solution was cooled to 0 ° C., 990 parts by mass of 4,4′-oxydiphthalic anhydride was added, and the mixture was stirred for 17 hours. . A pale yellow and viscous polyamic acid solution (2) was obtained. The solution obtained had a ηsp / C of 3.1 dl / g.

[Preparation of polyamic acid solution (3)]
(PMDA / p-DAMBO: ODPA / TPER = 95: 5)
After purging the inside of the reaction vessel equipped with a nitrogen introduction tube, a thermometer, and a stirring rod with nitrogen, 303 parts by mass of 5-amino-2- (p-aminophenyl) benzoxazole and 1,3-bis (4-aminophenoxy) 21 parts by mass of benzene was charged. Next, after adding 3000 parts by mass of N, N-dimethylacetamide and completely dissolving it, Snowtex (trade name) DMAC-Zl (manufactured by Nissan Chemical Industries, Ltd.) obtained by dispersing colloidal silica in dimethylacetamide. Add 5 parts by weight (including 8.1 parts by weight of silica), add 293 parts by weight of pyromellitic dianhydride and 22 parts by weight of 4,4′-oxydiphthalic anhydride, and stir at a reaction temperature of 25 ° C. for 50 hours. As a result, a pale yellow and viscous polyamic acid solution (3) was obtained. Ηsp / C of the obtained solution was 2.64 dl / g.

[Preparation of polyamic acid solution (4)]
(PMDA / p-DAMBO: ODPA / TPER = 90: 10)
After purging the inside of the reaction vessel equipped with a nitrogen introduction tube, a thermometer, and a stirring rod with nitrogen, 282 parts by mass of 5-amino-2- (p-aminophenyl) benzoxazole and 1,3-bis (4-aminophenoxy) 41 parts by mass of benzene was charged. Next, after adding 3000 parts by mass of N, N-dimethylacetamide and completely dissolving it, Snowtex (trade name) DMAC-Zl (manufactured by Nissan Chemical Industries, Ltd.) obtained by dispersing colloidal silica in dimethylacetamide. Add 5 parts by mass (including 8.1 parts by mass of silica), add 273 parts by mass of pyromellitic dianhydride and 43 parts by mass of 4,4′-oxydiphthalic anhydride, and stir at a reaction temperature of 25 ° C. for 50 hours. As a result, a pale yellow and viscous polyamic acid solution (4) was obtained. The obtained solution had a ηsp / C of 2.95 dl / g.

[Preparation of polyamic acid solution (5)]
(PMDA / p-DAMBO: ODPA / TPER = 80: 20)
After purging the inside of the reaction vessel equipped with a nitrogen introduction tube, a thermometer, and a stirring rod with nitrogen, 242 parts by mass of 5-amino-2- (p-aminophenyl) benzoxazole and 1,3-bis (4-aminophenoxy) 79 parts by mass of benzene was charged. Next, after adding 3000 parts by mass of N, N-dimethylacetamide and completely dissolving it, Snowtex (trade name) DMAC-Zl (manufactured by Nissan Chemical Industries, Ltd.) obtained by dispersing colloidal silica in dimethylacetamide. Add 5 parts by weight (including 8.1 parts by weight of silica), add 234 parts by weight of pyromellitic dianhydride and 83 parts by weight of 4,4′-oxydiphthalic anhydride, and stir at a reaction temperature of 25 ° C. for 50 hours. As a result, a pale yellow and viscous polyamic acid solution (5) was obtained. The solution obtained had a ηsp / C of 2.37 dl / g.

[Preparation of polyamic acid solution (6)]
(PMDA / p-DAMBO: ODPA / TPER = 75: 25)
After purging the inside of the reaction vessel equipped with a nitrogen introduction tube, a thermometer, and a stirring rod with nitrogen, 282 parts by mass of 5-amino-2- (p-aminophenyl) benzoxazole and 1,3-bis (4-aminophenoxy) 41 parts by mass of benzene was charged. Next, after adding 3000 parts by mass of N, N-dimethylacetamide and completely dissolving it, Snowtex (trade name) DMAC-Zl (manufactured by Nissan Chemical Industries, Ltd.) obtained by dispersing colloidal silica in dimethylacetamide. Add 5 parts by mass (including 8.1 parts by mass of silica), add 273 parts by mass of pyromellitic dianhydride and 43 parts by mass of 4,4′-oxydiphthalic anhydride, and stir at a reaction temperature of 25 ° C. for 50 hours. As a result, a pale yellow and viscous polyamide acid solution (6) was obtained. The obtained solution had a ηsp / C of 2.18 dl / g.

[Preparation of polyamic acid solution (7)]
(PMDA / p-DAMBO: ODPA / TPER = 50: 50)
After the inside of the reaction vessel equipped with a nitrogen introduction tube, a thermometer, and a stirring rod was purged with nitrogen, 138 parts by mass of 5-amino-2- (p-aminophenyl) benzoxazole and 1,3-bis (4-aminophenoxy) 178 parts by mass of benzene was charged. Next, after adding 3000 parts by mass of N, N-dimethylacetamide and completely dissolving it, Snowtex (trade name) DMAC-Zl (manufactured by Nissan Chemical Industries, Ltd.) obtained by dispersing colloidal silica in dimethylacetamide. Add 5 parts by weight (including 8.1 parts by weight of silica), add 133 parts by weight of pyromellitic dianhydride and 189 parts by weight of 4,4′-oxydiphthalic anhydride, and stir at a reaction temperature of 25 ° C. for 50 hours. As a result, a pale yellow and viscous polyamic acid solution (7) was obtained. The obtained solution had a ηsp / C of 2.06 dl / g.

[Preparation of polyamic acid solution (8)]
(PMDA / p-DAMBO: ODPA / TPER = 80: 20)
After replacing the inside of the reaction vessel equipped with a nitrogen introduction tube, a thermometer, and a stirring bar with nitrogen, 397 parts by mass of the polyamic acid solution (1) and 135 parts by mass of the polyamic acid solution (2) were added, and the reaction was performed at 25 ° C. After stirring at temperature for 10 hours, a pale yellow and viscous polyamic acid solution (8) was obtained. Ηsp / C of the obtained solution was 3.41 dl / g.

[Preparation of polyamic acid solution (9)]
(PMDA / PDA: ODPA / TPER = 90: 10)
After the inside of the reaction vessel equipped with a nitrogen introduction tube, a thermometer, and a stirring rod was purged with nitrogen, 176 parts by mass of paraphenylenediamine and 53 parts by mass of 1,3-bis (4-aminophenoxy) benzene were charged. Next, after adding 3000 parts by mass of N, N-dimethylacetamide and completely dissolving it, Snowtex (trade name) DMAC-Zl (manufactured by Nissan Chemical Industries, Ltd.) obtained by dispersing colloidal silica in dimethylacetamide. Add 5 parts by mass (including 8.1 parts by mass of silica), add 354 parts by mass of pyromellitic dianhydride and 56 parts by mass of 4,4′-oxydiphthalic anhydride, and stir at a reaction temperature of 25 ° C. for 50 hours. As a result, a pale yellow and viscous polyamide acid solution (9) was obtained. The obtained solution had a ηsp / C of 1.96 dl / g.

(Example 1)
The polyamic acid solution (3) was coated on the non-lubricant surface of a polyethylene terephthalate film (Toyobo Co., Ltd., A-4100, thickness 188 μm) using a comma coater (gap: 230 μm, coating width). 700 mm) and dried at 110 ° C. for 15 minutes to obtain a polyamic acid film having a thickness of 18 μm.
The above polyamic acid film is passed through a pin tenter having three heat treatment zones, the first stage 150 ° C. × 2 minutes, the second stage 220 ° C. × 2 minutes, the third stage 475 ° C. × 4 minutes, and slit to 500 mm width. Thus, a polyimide film having a thickness of 10 μm was obtained.
The above film is mounted on a continuous sputtering apparatus, RF sputter method is performed in an argon atmosphere using a nickel-chromium (chromium content 10%) alloy target under the conditions of frequency 13.56 MHz, output 400 W, gas pressure 0.8 Pa. Thus, a nickel-chromium alloy film having a thickness of 50 mm was formed at a rate of 10 mm / sec. Subsequently, copper was vapor-deposited at a rate of 100 Å / second to form a copper thin film having a thickness of 0.3 μm. Thereafter, this film is cut out to 250 mm × 400 mm, fixed to a plastic frame, and a thick copper plating layer having a thickness of 8 μm is formed on the copper thin film using a copper sulfate plating bath. A film was obtained.

After the metallized film to be measured was processed into a TAB tape pattern with a wiring width of 90 μm, the peel strength was defined as the strength required when the metallized film was peeled off in the 90-degree direction. The measurement was performed using a tensile tester (manufactured by Shimadzu Corporation, Autograph (registered trademark) model name AG-5000A) according to JIS C6418. Tables 1 and 2 show characteristics of the obtained polyimide film.

(Example 2)
The polyamic acid solution (4) is coated on a non-lubricant surface of a polyethylene terephthalate film (Toyobo Co., Ltd., A-4100, thickness 188 μm) using a comma coater (gap is 230 μm, coating width). 700 mm) and dried at 110 ° C. for 15 minutes to obtain a polyamic acid film having a thickness of 18 μm. The above polyamic acid film is passed through a pin tenter having three heat treatment zones, the first stage 150 ° C. × 2 minutes, the second stage 220 ° C. × 2 minutes, the third stage 475 ° C. × 4 minutes, and slit to 500 mm width. Thus, a polyimide film having a thickness of 10 μm was obtained. Thereafter, a metal laminated polyimide film was obtained in the same manner as in Example 1. Tables 1 and 2 show characteristics of the obtained film.

(Example 3)
The polyamic acid solution (5) was coated on a non-lubricant surface of a polyethylene terephthalate film (Toyobo Co., Ltd., A-4100, thickness 188 μm) using a comma coater (gap: 230 μm, coating width). 700 mm) and dried at 110 ° C. for 15 minutes to obtain a polyamic acid film having a thickness of 18 μm.
The above polyamic acid film is passed through a pin tenter having three heat treatment zones, the first stage 150 ° C. × 2 minutes, the second stage 220 ° C. × 2 minutes, the third stage 475 ° C. × 4 minutes, and slit to 500 mm width. Thus, a polyimide film having a thickness of 10 μm was obtained.
Thereafter, a metal laminated polyimide film was obtained in the same manner as in Example 1. Tables 1 and 2 show characteristics of the obtained film.

Example 4
The polyamic acid solution (8) was coated on the non-lubricant surface of a polyethylene terephthalate film (Toyobo Co., Ltd., A-4100, thickness 188 μm) using a comma coater (gap: 230 μm, coating width). 700 mm) and dried at 110 ° C. for 15 minutes to obtain a polyamic acid film having a thickness of 18 μm.
The above polyamic acid film is passed through a pin tenter having three heat treatment zones, the first stage 150 ° C. × 2 minutes, the second stage 220 ° C. × 2 minutes, the third stage 475 ° C. × 4 minutes, and slit to 500 mm width. Thus, a polyimide film having a thickness of 10 μm was obtained.
Thereafter, a metal laminated polyimide film was obtained in the same manner as in Example 1. Tables 1 and 2 show characteristics of the obtained film.

(Example 5)
The polyamic acid solution (6) was coated on the non-lubricant surface of a polyethylene terephthalate film (Toyobo Co., Ltd., A-4100, thickness 188 μm) using a comma coater (gap: 230 μm, coating width). 700 mm) and dried at 110 ° C. for 15 minutes to obtain a polyamic acid film having a thickness of 18 μm.
The above polyamic acid film is passed through a pin tenter having three heat treatment zones, the first stage 150 ° C. × 2 minutes, the second stage 220 ° C. × 2 minutes, the third stage 475 ° C. × 4 minutes, and slit to 500 mm width. Thus, a polyimide film having a thickness of 10 μm was obtained.
Thereafter, a metal laminated polyimide film was obtained in the same manner as in Example 1. Tables 1 and 2 show characteristics of the obtained film.

(Example 6)
The polyamic acid solution (4) was coated on the non-lubricant surface of a polyethylene terephthalate film (Toyobo Co., Ltd., A-4100, thickness 188 μm) using a comma coater (gap: 115 μm, coating width). 700 mm) and 7.5 minutes at 110 ° C. to obtain a polyamic acid film having a thickness of 9 μm.
The above polyamic acid film is passed through a pin tenter having three heat treatment zones, the first stage 150 ° C. × 2 minutes, the second stage 220 ° C. × 2 minutes, the third stage 475 ° C. × 4 minutes, and slit to 500 mm width. Thus, a polyimide film having a thickness of 5 μm was obtained.
Thereafter, a metal laminated polyimide film was obtained in the same manner as in Example 1. Tables 1 and 2 show characteristics of the obtained film.

(Example 7)
The polyamic acid solution (9) was coated on a non-lubricant surface of a polyethylene terephthalate film (A-4100, thickness: 188 μm, manufactured by Toyobo Co., Ltd.) using a comma coater (gap: 230 μm, coating width). 700 mm) and dried at 110 ° C. for 15 minutes to obtain a polyamic acid film having a thickness of 18 μm.
The above polyamic acid film is passed through a pin tenter having three heat treatment zones, the first stage 150 ° C. × 2 minutes, the second stage 220 ° C. × 2 minutes, the third stage 475 ° C. × 4 minutes, and slit to 500 mm width. Thus, a polyimide film having a thickness of 10 μm was obtained.
Thereafter, a metal laminated polyimide film was obtained in the same manner as in Example 1. Tables 1 and 2 show characteristics of the obtained film.

(Comparative Example 1)
The polyamic acid solution (2) is coated on a non-lubricant surface of a polyethylene terephthalate film (Toyobo Co., Ltd., A-4100, thickness 188 μm) using a comma coater (gap is 230 μm, coating width). 700 mm) and dried at 110 ° C. for 15 minutes to obtain a polyamic acid film having a thickness of 18 μm.
The above polyamic acid film is passed through a pin tenter having three heat treatment zones, the first stage 150 ° C. × 2 minutes, the second stage 220 ° C. × 2 minutes, the third stage 400 ° C. × 4 minutes, and slit to 500 mm width. Thus, a polyimide film having a thickness of 10 μm was obtained.
Thereafter, a metal laminated polyimide film was obtained in the same manner as in Example 1. Tables 1 and 2 show characteristics of the obtained film. Although the obtained film was highly adhesive, it was a film having a high CTE.

(Comparative Example 2)
The polyamic acid solution (1) was coated on the non-lubricant surface of a polyethylene terephthalate film (Toyobo Co., Ltd., A-4100, thickness 188 μm) using a comma coater (gap: 230 μm, coating width). 700 mm) and dried at 110 ° C. for 15 minutes to obtain a polyamic acid film having a thickness of 18 μm.
The above polyamic acid film is passed through a pin tenter having three heat treatment zones, the first stage 150 ° C. × 2 minutes, the second stage 220 ° C. × 2 minutes, the third stage 400 ° C. × 4 minutes, and slit to 500 mm width. Thus, a polyimide film having a thickness of 10 μm was obtained.
Thereafter, a metal laminated polyimide film was obtained in the same manner as in Example 1. Tables 1 and 2 show characteristics of the obtained film. The obtained film was a film having low CTE but low adhesion.

(Comparative Example 3)
The polyamic acid solution (7) was coated on a non-lubricant surface of a polyethylene terephthalate film (Toyobo Co., Ltd., A-4100, thickness 188 μm) using a comma coater (gap: 230 μm, coating width). 700 mm) and dried at 110 ° C. for 15 minutes to obtain a polyamic acid film having a thickness of 18 μm.
The above polyamic acid film is passed through a pin tenter having three heat treatment zones, the first stage 150 ° C. × 2 minutes, the second stage 220 ° C. × 2 minutes, the third stage 400 ° C. × 4 minutes, and slit to 500 mm width. Thus, a polyimide film having a thickness of 10 μm was obtained.
Thereafter, a metal laminated polyimide film was obtained in the same manner as in Example 1. Tables 1 and 2 show characteristics of the obtained film. Although the obtained film was highly adhesive, it was a film having a high CTE.

<Manufacture of double-sided COF and multilayer substrate>
The double-sided metal laminated polyimide film obtained in Example 1 was slit into a width of 250 mm, and a sprocket hole for conveyance, a hole for alignment, and a through-hole connection hole were punched at both ends. Next, after passing through a direct metallization process through a roll-to-roll type desmear treatment apparatus and conducting the through-hole portion, through-hole plating was performed by a roll-to-roll type continuous electroplating apparatus.
After plating, through a double-sided circuit processing process using a normal dry film resist, a predetermined pattern was exposed and developed, and then the patterned resist was used as a mask and etching was performed using an aqueous ferric chloride solution. . After removing the resist, apply a liquid resist type solder resist leaving the pad part, dry, mask exposure and development, and apply 1.5 μm thick tin plating to the pad part, and use each polyimide film roll A printed wiring board (COF film substrate) roll having a length of 250 mm and a length of about 300 m was obtained and wound on a reel. The circuit portion with the narrowest line width of each of the obtained COF film substrates had a line width / line spacing = 45/55 μm.
An adhesive sheet (Pyrarax LF) was sandwiched between the three double-sided COFs, and press-laminated at 180 ° C. and 20 MPa for 15 minutes. Then, using a NC drill machine, a through hole having a hole diameter of 200 μm was prepared at a drill rotation speed of 12000 rpm. A 10-layer multilayer circuit board was fabricated by interlayer connection of the inner surface of the through hole by electroless plating and electrolytic plating. The obtained multilayer circuit board was a highly reliable board having good appearance, no warping, and no poor connection.
All the multilayer circuit boards produced using the metal laminated polyimide film of Example 2-7 by the same method as described above were able to obtain highly reliable boards having good appearance, no warping, and no poor connection.

  The polyimide film obtained from the polyimide of the present invention is excellent in bonding with a metal thin film or metal foil at high temperature, and is a flexible metal laminated board free from deformation, warpage, distortion at high temperature, for example, an interlayer such as a flexible printed circuit board It is extremely useful as an insulating layer, and deformation of a polyimide film as a base material can be suppressed during pressure heating molding when forming the insulating layer. The polyimide film of the present invention, which has high tensile breaking strength, high tensile modulus, and linear expansion coefficient in the low surface direction, is excellent in surface adhesion and is obtained when used for interlayer insulation such as multilayer printed wiring boards. The multilayer printed wiring board can be made lighter (lighter and thinner), and is useful for enhancing the functionality, performance, and miniaturization of electronic devices.

Claims (6)

A polyimide having a structural unit of the following [Chemical Formula 1], wherein at least R1 is a residue of an aromatic tetracarboxylic acid selected from [Chemical Formula 2], and R2 is an aromatic diamine selected from [Chemical Formula 3] 1-30 mol% of polyimide (a) having a residue,

At least pyromellitic acid residue and / or biphenyltetracarboxylic acid residue as aromatic tetracarboxylic acid residue, diamine residue having benzoxazole skeleton and / or phenylenediamine residue as aromatic diamine residue A polyimide comprising 70 to 99 mol% of a polyimide (b) containing   A polyimide film having a tensile strength at break of 300 MPa or more and a tensile modulus of elasticity of 5 GPa or more obtained from the polyimide according to claim 1.   The polyimide film according to claim 2, wherein the linear expansion coefficient in the plane direction is 0 to 30 ppm / ° C.   A copper-clad laminate using the polyimide film according to claim 2 as a substrate.   The printed wiring board formed by removing a part of copper layer of the copper clad laminated board of Claim 4, and forming a circuit pattern.   The multilayer circuit board using the polyimide film and / or printed wiring board in any one of Claims 2-5.